1. Field of Invention
The present invention relates to valve stem seal assemblies for use in internal combustion engines, and more particularly to the design and construction of valve stem seal components for facilitating assembly and installation thereof onto valve guides of said engines.
2. Description of the Prior Art
Intake and exhaust valves are employed in cylinder heads of internal combustion engines. Such valves, supported for reciprocal motion within valve guides, include integral elongated stems extending from within the engine cylinder heads, the ends of the stems typically interacting with rotating overhead cams for cyclic opening and closing of the valves against the force of valve return springs during the combustion cycle. In order to permit unobstructed reciprocal movement of the stem in the guide, some mechanical clearance must obviously exist between the valve guide and the moving stem. In fact, a plurality of such valve stems move reciprocally in valve guides, to and from the cylinder head, each within its individual guide. So-called valve stem seal assemblies are used to seal against leakage of oil through a mechanical clearance path between each annular engine valve guide and its associated valve stem.
As is well known, the intake port of a combustion chamber is opened and closed by the reciprocating motion of at least one intake valve, which in turn is driven by the rotary motion of a cam, the latter being affixed to and rotatable with an engine camshaft. The intake valve permits fuel mixed with air to flow into the combustion chamber. In addition, an internal combustion engine has at least one exhaust valve and associated exhaust port for releasing expended combustion gases to the atmosphere. Typically, intake and exhaust valves are of similar construction and both include stems integrally affixed to the valves.
In some engines, a unitary elastomeric valve stem seal component is fitted over or atop each valve guide, wherein the seal component is frictionally mounted directly to the guide. In other cases the seal is encased within or otherwise secured to a rigid, typically metal, seal retainer to form an assembly to assure proper securement of the seal to the guide. Those skilled in the art will appreciate that pluralities of such elastomeric valve stem seal components are employed in typical engines.
In the case of small engines, for example those used in lawnmowers, V-style engines have become popular with one cylinder in each V-bank. In some cases, only one valve stem seal component is employed per cylinder, the one valve stem seal component being located at the intake valve of the cylinder. In such cases, the exhaust valve is operated without a valve stem seal component. During assembly, since the guides of intake and exhaust valves look alike, an installer can become confused, inserting the seal component on the exhaust valve instead of on the intake valve.
The improved valve stem seal component of the present invention overcomes the occasional and or potential confusion issues associated with installation of valve stem seals on an intake valve, particularly in cases where no valve stem seal is to be used on the exhaust valve. The component also streamlines valve stem seal component installation, and thus promotes a more cost-effective assembly line process.
The invention provides an integral position locator on a valve stem seal component having a seal module adapted for installation directly atop of a valve guide of an internal combustion engine. A plurality of such seal components are contemplated for use in an engine, each component designed for insertion over a seal module on at least the intake valve guide of each cylinder.
In the described embodiment, the valve stem seal component includes the valve stem seal module adapted to be directly installed over an intake valve guide. The locator is attached to the module via an integral radial connection portion that extends between the module and the locator. In the described embodiment, the locator is a circular ring adapted to be installed over the exhaust guide.
Finally, the radial connection portion includes an arcuate edge adapted to fit only in one orientation against a curvilinear edge of a protruding boss on the cylinder head. In addition, both the radial connection portion and the protruding boss contain matching indicia to assure proper correspondence and hence placement by the installer during assembly of the valve stem seal component.